This study examines the association of degree of local implementation of a state-mandate hospital diversion intervention with use of inpatient psychiatric hospital services. The multi-faceted hospital diversion intervention resulting from the Washington State Mental Health Act of 1989 focuses upon individuals who have previously been identified as "high utilizers" of those services. In Washington State, high utilizers are defined as those individuals who in a two year period experience three or more hospital episodes or one hospitalization of thirty days or more. Level of implementation will be assessed in local mental health catchment areas (Regional Support Networks or RSNs) in the state. Key research questions are: l) Are there differences among regions (RSNs) in implementation of Washington State's model for hospital diversion? How do regions differ in implementation? 2) Do population characteristics (age, gender, ethnicity, diagnostic category, prior hospital use) of high utilizers change over time? 3) How does hospital use vary for subgroups of high utilizers according to age, gender, race, and diagnosis? Is variation consistent across regions? 4) How does hospital use vary for subgroups of high utilizers according to amount of prior hospital use? 5) How do regional differences in overall implementation impact hospital use by high utilizers? 6) Do differences in implementation of specific components make a difference in hospital use by high utilizers? Subjective and objective measures will be used to assess the level of implementation. Each element of the intervention represents the following core constructs from the mental health service literature on hospital diversion: l) systems integration, 2) case management services targeted to high utilizers, 3) crisis response services, 4) residential services, and 5) continuity of care. Dependent measures include l) number of days per year in hospital residence, 2) reduction in number of days per year in hospital residence 3) number of hospital episodes per year, and 4) reduction in number of episodes per year.